Electromagnetic device



I P 8, 1942- E. bIcKTEN, JR 2,295,390

ELECTROMAGNETIC DEVICE Filed July 11, 1940 FIG. F/GZZ FIG. 3

FIG. 6 57 5 7 50 49 54L! (56' J2 .sua. I

lNl/ENTOR E. DICK 7' EM JR.

ATTORNEY Patented Sept. 8, 1942 UNITED STATES PATENT OFFICE ELECTROMAGNETIC DEVICE Emil Dickten, Jr., Totowa, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 11, 1940, Serial No. 344,900

2 Claims. (Cl. 175339) This invention relates to electromagnetic de- The relay of Figs. 1 and 2 has a core I, the rear vices and more particularly to devices which are end of which is widened to form a heel-piece 2 polarized to be responsive to current of but one and is bifurcated to form two sections bent in polarity, opposite directions to provide mounting ears 3 The object of the invention is to enable the 5 and 4 by which the relay may be attached to a modification of neutral relays Or electromagnetic mountin plate, and the forward end of which devices in a simple manner to render them secore is provided with a pole face 5. Mounted on lectively responsive to energizing current of a the core is an energizing coil 6 having a rear predetermined polarity. spoolhead I and a forward spoolhead 8. The U- This object is attained by bridging a portion 10 shaped armature 9 is positioned with its forward of the magnetic circuit of an electromagnetic cross-reach ill overlying the pole face 5 of the device by a permanent magnet thereby forming core and its side arms extending on either side a magnetic rectifier which admits the flow of of the coil 6 with their ends pivoted to the formagnetic flux to enable the device to operate ward edge of the heel-piece 2 by reed springs II'. when energizing current of a predetermined po- The cross-reach Ill of the armature is normally larity is applied to the operating coil of such biased against the back-stop nut l2 which is device and which impedes the flow of magnetic threaded upon one end of stud 13 secured in a flux to prevent the operation of the device when hole in the end of core I. The back-stop nut l2 energizing current of the opposite polarity is apserves as a means for limiting the releasing plied to the operating coil. In accordance with movement of the armature and for adjusting the the invention the permanent magnet bridge may length of the air-gap between the cross-reach be applied around the operating coil between the l0 of the armature and pole face 5 of the core I. Opposite ends of the core, may be applied between Insulatedly mounted on each end of the heelthe forward end of the core and the return polepiece 2 is a spring pile-up, each pile-up com- Diece, or may be bridged around a portion of the prising as many contact springs as may be recore. quired but as shown comprising springs l4, 15,

For a more comprehensive understanding of i6 and I! and a coil terminal lug 18. The the invention reference may be had to the folsprings and terminal lug of each pile-up are lowing detailed description taken in connection clamped to the heel-piece 2 between the clampwith the accompanying drawing in which: ing plates l9 and 20 by screws 2| which extend Fig. 1 is a top plan view of a neutral relay through aligned holes in the plate I9, spring I4, modified in accordance with the present invenlug l8, heel-piece 2, reed spring H, springs l5, tion; It and IT and through holes in insulation strips Fig. 2 is an end view of the relay disclosed in which insulate such springs and lugs from each other, from the heel-piece 2 and from the clamp- Fig. 3 is a perspective view, partly in cross-secing plates I 9 and 2B, and into threaded holes in tion, of a message register modified in accordthe clamping plate 28. The spring l5 of each ance with the present invention; pile-up engages an insulating stud 22 carried by Fig. 4 shows one of the permanent magnet supthe armature 9 whereby the springs I5 serve to porting details of Fig. 3; normally bias the armature against the back- Fig. 5 shows a core for an electromagnetic destop nut I2. The attraction of the armature tovice modified in accordance with the present inward the core through the studs 22 moves vention; springs I5, I 6 and ll of each pile-up into engage- Fi 6 shows the core of Fig. 5 partly in cross-. ment and moves spring l5 of each pile-up out section to better disclose the construction thereof engagement with the associated spring I 4. of; and For rendering the relay unidirectional or po- Fig. 7 is a circuit illustrative of one application larized in operation, a permanent bar magnet of the invention. 23 is positioned parallel to the core i and bridged Referring first to Figs. 1 and 2 the invention to the core around the outside of the coil 5 by has been illustrated as applied to a well-known spacing blocks 24 and 25 of magnetic material. type of neutral relay. It is to be understood, The block 24 is seated on the forward end of however, that while a particular type of relay the core I and the block 25 is seated on the heelis disclosed, neutral relays of other types could piece 2 and each block is provided with grooves be modified in the same manner to function as in the edges thereof. For securing the magnet unidirectional or polarized relays. 23 to the core I screws 26 are provided which extend through holes in the clamping plate 21 on either side of the magnet 23, lie in the grooves in the edges of the blocks 24 and 25 and enter threaded holes in the core I and heel-piece 2 of the core. The poles of the permanent magnet are thus magnetically connected to the ends of the core and the magnet is bridged around that portion of the core on which the coil 6 is supported. With the permanent magnet thus connected a flow of flux is set up in the core I which may be visualized as leaving the north pole of the magnet, entering the heel-piece 2 through block 25, flowing forwardly through the core I and entering the south pole of the magnet through block 24 thereby substantially saturating the core I.

If current of a predetermined polarity is now applied to the coil 6, a coil flux will be set up in the core I which will flow rearwardly through the core, returning through the side arms of the armature 9 and the cross-reach l thereof, across the air-gap to the forward end of the core. The coil flux will therefore oppose the permanent magnet flux in the core i and the flux density in the core is therefore decreased whereby flux readily flows across the air-gap between the crossreach and the end of the core I whereupon the armature 9 becomes attracted to operate the springs of the spring pile-ups.

If current of the opposite polarity is applied to the coil 6, a coil flux will be set up in the core I which will tend to flow forwardly through the core I and thus aid the permanent magnet flux, but, since the core I is almost or entirely saturated due to the flux from the permanent magnet,

the increase in flux in the core will be slight or nil and practically no flux will flow across the air-gap between the armature and the forward end of the core and therefore the armature will be unaffected.

Fig. 3 illustrates the application of the invention to an electromagnetic device, for example, to a subscribers message register of well-known construction. The register is provided with a U- shaped return pole-piece 28 having legs 29 and 39 and to the base of which a core is secured which extends forwardly between the legs 29 and 39. The core is provided with a rear threaded portion 3| which extends through a hole in the base of the return pole-piece and upon which a nut 32 is threaded for clamping the core to the pole-piece. Mounted upon the core is an operating coil 33 having rear and forward spoolheads 34 and 35. Supported on the core between the rear spoolhead 34 and the base of the return pole-piece is a rear permanent magnet support 36 and supported on the forward end of the core beyond the front spoolhead is a front permanent magnet support 31. These supports are of magnetic material and each is, as most clearly shown in Fig. 4, provided with a central opening 38 through which the core extends and with a recessed portion 39 in its upper edge of sufhcient extent to receive the end of a permanent bar magnet 49.

An armature (not shown) is pivoted between the forward ends of the legs 29 and 30 of the return pole-piece for cooperation with the forward end of the core and the forward ends of the legs 29 and 39 are held in spaced relationship to each other and to the forward end of the core by a plate 42 of non-magnetic material secured to the legs 29 and 30 by screws 4|. A mounting member 43 for the message register mechanism is also secured to the forward ends of the legs 29 and 30 by the screws 44, such mechanism being positioned beneath the dust cover 45.

Due to the bridging of the ends of the core through the supports 35 and 31 and through the permanent magnet 40 the message register armature will be attracted towards the forward end of the core in the manner previously described in connection with the relay of Fig. 2, only when current of a predetermined polarity is applied to the coil 33.

The bridging effect may also be accomplished in the core itself as illustrated in Figs. 5 and 6 by fabricating the core in three sections. The rear section of the core 49 is provided with a reduced threaded portion 50 by means of which the core assembly may be secured to the return pole-piece and has an axially formed socket 5| in its forward end. The forward section 52 of the core is provided with a shouldered portion 53 adjacent its forward end and with a shouldered portion 54 on its rear end which may be inserted in the socket 5| of the rear core section 49 as disclosed in Fig. 6. The shank 55 of the forward core section 52 of the core between the shouldered portions 53 and 54 is reduced in diameter. Supported on the shouldered portions 53 and 54 of the forward core section is a tubular permanent magnet 56. In order that the three sections of the core may be held in their assembled position, the shouldered portions 53 and 54 are of such a diameter that they have a driving fit in the tubular magnet 56 and in the socket 51 of the rear section. It will be noted that due to the reduced diameter of the shank 55 the permanent magnet engages the core sections 49 and 52 only at its polar ends and that it therefore constitutes a bridge of the shank 55, so that the shank is normally almost or entirely saturated by the flux from the permanent magnet which may be visualized as leaving the north pole of the magnet, entering the shouldered portion 54, flowing through the shank 55 and entering the south pole of the magnet through the shouldered portion 53. The core structure disclosed in Figs. 5 and 6 may be employed to replace the usual core of an electromagnetic device, such as a message register of the type shown in Fig. 3, for rendering such device responsive to current of a predetermined polarity, no other change in the structure of the device being necessary.

If it is desired to render the electromagnetic devices illustrated responsive to operating current of the opposite polarity all that is required is to reverse the connection of the coil terminals to the operating circuit. For example, if two such identical devices are connected in series in an operating circuit and the coils are reversely connected one device will operate on current of one polarity and the other device will operate on current of the reverse polarity.

As illustrative of one application of a polarized electromagnetic device of the type illustrated, for example, in Fig. 3, Fig. 7 shows a two-party telephone line having substations 51 and 58 thereon, terminating in the bank of a line finder 59. The line is equipped with the usual line relay 60 which is operable upon the initiation of a call from either substation of the line to cause an idle line finder to connect with the line, and with the usual cut-off relay 6| which is operable when the calling line has been seized by a line finder to open the operating circuit of the line relay 60. For metering calls initiated by either substation 51 or 58 two serially connected message registers 62 and 63 of the type disclosed in Fig. 3 or as modified in accordance with Figs. 5 and 6 may be employed. Register 62 is allocated to substation 51 and register 53 is allocated to substation 53 and such registers are oppositely polarized.

Should the party line subscriber at substation 5'! initiate a call, the metering switch 64 will at the appropriate time be so operated as to connect the negatively poled battery 65 in a circuit over metering brush 6! of line finder 5%, bank terminal 68, back contact of relay 63, thence through the windings of message register magnets 62 and 63 to ground whereby only register 62 will be operated. Should the party line subscriber at substation 58 initiate a call, the metering switch 64 will at the appropriate time be so operated as to connect the positively poled battery 66 into the previously traced metering circuit whereby only register 53 will be operated.

What is claimed is:

1. In an electromagnetic structure, a core of magnetic material, an operating coil thereon and an armature cooperating with said core, said core comprising a continuous intermediate portion of reduced diameter provided with flanged ends and a tubular permanent magnet surrounding said portion with only its polar ends in engagement with the flanged ends of said reduced portion thereby bridging that portion of said core, the coil located to surround the said intermediate portion and magnet whereby said armature is attracted toward said core only when said coil is energized by current of a predetermined polarity.

2. In an electromagnetic structure, a core, an operating coil thereon and an armature cooperating with said core, said core comprising a rear section having a socket in the outer end thereof, a front section having a rearwardly extending shank portion the rear end of which is seated in said socket, said shank being reduced in diameter throughout the major portion of its length and a tubular permanent magnet supported on said shank portion between said rear and front sections with only its polar ends in engagement with said rear and front sections thereby bridging said shank portion, whereby said armature is attracted towards said core only when said coil is energized by current of a predetermined polarity.

. EMIL DICKTEN, JR. 

